Method for manufacturing archery bow risers and the archery bows including the risers produced by the method

ABSTRACT

A method for manufacturing an archery bow riser of hollow construction by the tubular hydroforming process and the risers produced by the method.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] There are no related applications.

STATEMENTS AS TO RIGHTS TO INVENTION MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

[0002] The invention disclosed and claimed herein was not made under anyfederally sponsored research and development program.

A. BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] This invention concerns a method for manufacturing archery bowrisers and the archery bows including such risers produced by themethod.

[0005] 2. Description of the Prior Art

[0006] Archery bow risers, particular archery bow risers for use withcompound bows, are required to be strong enough to withstand the largeforces produced by the limbs during firing of the bow. In the past,risers possessing such strength have been manufactured by variousprocesses including the milling of aluminum blocks or billets, thecasting of magnesium and aluminum in molds and the extruding ofaluminum. A disadvantage of these processes is that the risers soproduced are heavy and contribute significantly to the weight of thebow. Users of such bows, for example hunters in the fields, would preferthat the bows be lighter in weight.

[0007] The production of shaped parts by a process referred to as tubehydroforming has become popular in recent times, particularly for partsused in the automotive industry. The process involves placing either astraight metal tube, or a metal tube prebent into the general overallshape of the part to be formed, into a hydraulically activated die. Thedie cavity is in the shape of the part to be formed. The die parts arethen closed and pressurized water is forced into the ends of the tubecausing the tube to expand outwardly into the shape of the die cavities.The principal benefit of tube hydroforming is the significant weightsaving that is achieved by a hollow component. Other reported benefitsof tube hydroforming include part consolidation (i.e., the advantage ofusing a one piece hollow tube instead of stamping and welding two ormore pieces); weight reduction through enhanced control of wallthickness; lower tooling costs; reduced dimensional variations andreduced amount of scrap material. Adding to the popularity of tubehydroforming in recent times has been the advanced software programmingwhich allows more finely tuned movement of the dies and the resultantproduction of parts to exacting specifications. It is not believed thatthe tube hydroforming process has been previously utilized to producearchery bow risers.

B. SUMMARY OF THE INVENTION

[0008] The present invention is directed to a method for manufacturingan archery bow riser of hollow construction by the tubular hydroformingprocess and the archery bow risers produced by that method. It isbelieved that such a hollow construction riser will be able to withstandthe significant forces produced by the limbs because most of the riserstrength which withstands the limb forces is at the outer edges of theriser and therefore any riser strength lost by the hollow interiorconstruction is not critical.

[0009] The process for manufacturing an archery bow of hollowconstruction involves prebending a hollow metal tube into the generaloverall shape of the riser. The riser shape may, for example, includegrip attachment surfaces, a bow sight mounting surface, and limbattachment areas. The bent tube is then placed into a cavity in a lowerhydraulically activated die. The cavity is in the shape of a firstsurface of the riser to be formed and includes, for example, the shapeof the grip area, arrow shelf and/or bow sight mounting surface. Anupper hydraulically activated die includes a cavity in the shape of asecond surface of the riser to be formed. The upper and lower dies areclosed about the bent tube and water under pressure is forced into theends of the tube. The combination of the closure of the dies and theinternal water pressure in the tube deforms the bent tube into the shapeof the cavities in the dies. The dies are then separated and the riseris removed.

[0010] Accordingly, it is an object of this invention to form a lightweight archery bow riser by means of a hydroforming process;

[0011] It is a further object of this invention to form a light weightarchery bow riser including grip attachment surfaces by means of ahydroforming process;

[0012] It is an additional object of this invention to form a lightweight archery bow riser including a bow sight mounting surface by meansof a hydroforming process;

[0013] It is a still further object of this invention to form a lightweight archery bow riser including limb attachment areas by means of ahydroforming process; and

[0014] It is another object of this invention to form a light weightarchery bow riser including a grip portion, an arrow shelf and a bowsight mounting surface by means of a hydroforming process.

[0015] Other objects and attendant advantages of this invention will bereadily appreciated as the same becomes more clearly understood byreferences to the following detailed description when considered inconnection with the accompanying drawings in which like referencenumerals designate like parts throughout the figures thereof.

C. BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a side elevational view of an archery bow including theriser produced according to the present invention;

[0017]FIG. 1A is a front elevational view of the archery bow shown inFIG. 1;

[0018]FIG. 2 is a perspective view of the tubular extrusion from whichthe riser of the present invention is formed;

[0019]FIG. 3 is a side view of the tubular extrusion shown in FIG. 2;

[0020]FIG. 4 is a top plan view of the tubular extrusion shown in FIG.2;

[0021]FIG. 5 is a side to side view of the prebent tubular extrusion;

[0022]FIG. 6 is a front to back view of the prebent tubular extrusion;

[0023]FIG. 7 is a top plan view of the prebent tubular extrusion;

[0024]FIG. 8 is a perspective view of the opened dies and the prebenttubular extrusion placed in a cavity of the lower die;

[0025]FIG. 9 is a perspective view of the closed dies and the prebenttubular extension located in the cavities of the upper and lower die;

[0026]FIG. 10 is a perspective view of the opened dies and the formedriser removed from the dies; and

[0027]FIG. 11 is a perspective view of the formed riser after the endsof the limb attachment areas have been further shaped to receive thelimb attachment devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] For a fuller understanding of the nature and objects of theinvention, reference should be had to the following detailed descriptiontaken in connection with the accompanying drawing forming a part of thisspecification and in which similar numerals of reference indicatecorresponding parts in all the figures of the drawing.

[0029] In FIG. 1 there is shown an archery bow 2 including a riser 4 ofthe type produced in accordance with the present invention. Riser 4includes grip attachment surfaces 6 to which grip 7 having an arrowshelf 8 thereon is secured by, for example, screws or adhesive. Riser 4includes a bow sight mounting surface 10 and limb attachment areas 9having angular surfaces 13 at the ends of riser 4. Riser 4 is connectedat one end to an upper limb 12 by a conventional limb attachment device11 and at the other end by conventional limb attachment device 11 to alower limb 14. The riser 4 is connected to the limb attachment devices11 by bolts 17. A dual feed cam 15 is mounted on an axle pin whichextends through the bottom of lower limb 14. A concentric pulley wheel16 is mounted on an axial pin which extends through the top of upperlimb 12.

[0030] A string has a medial portion trained around pulley wheel 16 toform bow string 18 and a secondary return string 20. The ends ofbowstring 18 and secondary return string 20 pass around eccentricperipheral groove portions of the cam 15 and are connected to it, sothat when the bow is fired, bow string 18 and return string 20 will befed out from cam 15. An anchor cable 22 is anchored at one end to theaxle which extends through the top of upper limb 12. The other end ofanchor cable 22 passes around an eccentric peripheral groove portion ofcam 15 and is connected to it. In this manner, anchor cable 22 forms adirect connection between the limbs 12 and 14. While the illustrated bowis a dual-feed single-cam compound bow of the type disclosed in U.S.Pat. No. 5,368,006, it will be understood that the riser produced inaccordance with the present invention may be used with other types ofbows as well.

[0031] The process for producing riser 4 begins with a tubular extrusion24 of the type shown in FIGS. 2 through 4. Tubular extrusion 24 whichmay, for example, be formed of aluminum or steel, includes a hollowinterior 26 and openings 23 and 25. Tubular extrusion 24 may, forexample, have a wall thickness of 0.125 inches, a height of 0.75 inchesand a width of 1.5 inches. The tubular extrusion 24 is then prebentmanually to the shape shown in FIGS. 5 through 7 so that it may fitwithin a cavity 19 of bottom die 28 shown in FIG. 8. The cavity 19 is inthe shape of a first surface of the riser to be formed and includes thearea of tubular extrusion 24 which will be formed into the gripattachment surfaces 6 and is shown generally as 6′, the area of tubularextrusion 24 which will be formed into the bow sight mounting surface 10and is shown generally as 10′, and the area of tubular extrusion 24which will be formed into the limb attachment areas 9 is shown generallyat 9′ in FIGS. 5 and 6.

[0032] In FIG. 8, the tubular extrusion 24 is shown in a cavity 19 inbottom die 28 prior to an upper die 30 and bottom die 28 being broughttogether and the internal fluid being injected under pressure into bothends of the tubular extrusion 24. Either upper die 30 may be moveddownwardly into contact with lower die 28 or lower die 28 may be movedupwardly into contact with upper die 30. Upper die 30 includes acorresponding cavity 21 in the shape of a second surface of the riser tobe formed. The next step is shown in FIG. 9 wherein upper die 30 andlower die 28 are brought into contact and internal fluid is injectedinto openings 23 and 25 of tubular extrusion 24 in the direction of thearrows. The pressure exerted by die 28 on tubular extrusion 24 may, forexample, be in the range of 40,000 to 60,000 pounds per square inch andthe pressure of the internal fluid injected into tubular extrusion 24may be in the range of 20,000 to 30,000 pounds per square inch. Duringthis step, the combination of the upper die 30 and the bottom die 28being closed on tube extrusion 24 and the internal fluid being injectedinto openings 23 and 25 of tube extrusion 24 forces the externalsurfaces of tube extrusion 24 to conform to the surface of cavity 19 inbottom die 28 and cavity 21 in upper die 28. In the next step shown inFIG. 10, the bottom die 28 and the upper die 30 of die 28 are separatedand the riser 4 is removed. The angular surfaces 13 of limb attachmentareas 9 are then further shaped by, for example, machining or coldsawing to enable the angular surfaces 13 to receive the limb attachmentdevices. A perspective view of the finished riser 4 is shown in FIG. 11.

[0033] This invention has been described above with reference topresently preferred embodiments of the invention; such description hasnot been presented as a catalog exhaustive of all forms which thisinvention may take. Accordingly, workers skilled in the art to whichthis invention pertains will readily appreciate that variations,alterations or modifications in the structures, procedures andarrangements described above may be practiced without departing from thescope of this invention. Thus, the foregoing description should not beread as limiting the scope of this invention to less than the fair scopeof the appended claims.

What is claimed as novel and desired to be secured by Letters Patent is:1. An archery bow having a riser and a pair of limbs attached to saidriser, characterized in that said riser is made from a tubular memberwhich is formed into the shape of the riser by a hydroforming process.2. An archery bow as recited in claim 1 wherein the tubular member is atubular extrusion.
 3. An archery bow as recited in claim 1 wherein thetubular member is prebent prior to being formed into the shape of theriser by the hydroforming process.
 4. An archery bow as recited in claim1 wherein the riser includes grip attachment surfaces.
 5. An archery bowas recited in claim 1 wherein the riser includes a bow sight mountingsurface.
 6. An archery bow as recited in claim 1 wherein the riserincludes limb attachment areas.
 7. A riser for use in an archery bowcharacterized in that said riser is made from a tubular member which isformed into the shape of the riser by a hydroforming process.
 8. A riseras recited in claim 7 wherein the tubular member is a tubular extrusion.9. A riser as recited in claim 7 wherein the tubular member is prebentprior to being formed into the shape of the riser by the hydroformingprocess.
 10. A riser as recited in claim 7 wherein the riser includesgrip attachment surfaces.
 11. A riser as recited in claim 7 wherein theriser includes a bow sight mounting surface.
 12. A riser as recited inclaim 7 wherein the riser includes limb attachment areas.
 13. A methodof manufacturing an archery bow riser of tubular construction by thehydroforming process, said method including the steps of: a) forming acavity in a bottom die, said cavity being in the shape of a firstsurface of the riser to be manufactured; b) placing a tubular member inthe cavity of the bottom die; c) forming a cavity in an upper die, saidcavity being in the shape of a second surface of the riser to bemanufactured; d) bringing said upper die and bottom die together whileinjecting fluid under pressure into said tubular member to form saidriser; and e) separating said upper die and bottom die and removing saidriser.
 14. A method of manufacturing an archery bow riser as recited inclaim 13 and including the further step of shaping the ends of the riserafter step e) to enable the ends of the riser to receive the limbattachment devices.
 15. A method of manufacturing an archery bow riseras recited in claim 13 wherein the fluid is injected under pressure intoopposite openings of said tubular member.
 16. A method of manufacturingan archery bow riser as recited in claim 13 wherein the tubular memberis prebent before it is placed in the cavity in the bottom die.
 17. Amethod of manufacturing an archery bow riser as recited in claim 13wherein said tubular member is a tubular extrusion.